Power Research at Georgia Tech

Dr. Deepak Divan, Fellow IEEEProfessor, IPIC Director

School of Electrical EngineeringGeorgia Institute of Technology

777 Atlantic Drive deepak.divan@ece.gatech.eduAtlanta, GA

Georgia Institute of Technology

Georgia Institute of Technology

• Premier research university with focus on technology.• Annual research budget >$349 million• Georgia Tech – Lorraine, Metz, France gives European presence• Ranked 5th in 2005 graduate engineering schools (US News &

World report)• 11,000 undergrads, 5,000 graduate students• College of Engineering – 1275 BS, 896 – MS and 181 – PhD

degrees awarded in 2003• Largest ECE Department in the US - 120 faculty, 1800 undergrad

students, 800 grad students• Strong presence in power, communications, nanotechnology,

MEMS and microelectronics, embedded systems, computing, organic electronics, signal & image processing and bio-medical

• Eight faculty working in the power area with competencies in power systems, power electronics, diagnostics, micropower, controls, and high voltage engineering

• Located in Atlanta – fast growing high-tech center.

Electric Power at Georgia Tech

Areas of Competency

Power Electronic Circuits & Converters

Electric Machines, Design & Protection

High Performance DC/DC Converters

Neural Networks in Power

Power Electronics in Power Systems

Power Systems Analysis & Planning

High Voltage Engineering

Photovoltaic Devices & Alternate Energy

Sensorless Diagnostics Using ANNs

Power Sensor Networks

World Renowned Faculty

•M. Begovic

•D. Divan

•T. Habetler

•R. Harley

•A. Meliopolous

•G. Rincon-Mora

•A. Rohatgi

•R. Webb•A balanced program covering education, research and tech-transfer•Eight full time faculty and 39 graduate students•NEETRAC program provides unique facilities & competencies

Basic Approach

• Strive for a balance between research, teaching and industry outreach

• As basic power electronics technology matures, the types of research conducted in universities v/s industries is shifting

• New research opportunities are emerging at the intersection of power electronics – distributed control – communications – and industrial/consumer/utility applications

• Diagnostics and prognostics, artificial intelligence and neural networks, wide area control, protection and uptime, integration of systems for manufacturability are all key drivers for the future

• Attracting US students into the power program is still a challenge

GT Power Research Program Structure

• IPIC does early-stage high-risk high-impact projects – consortium funded

• The power program at GT receives >$6M/year in funding, including NEETRAC

• IPIC projects have already led to funded projects and to commercialization

• Over 30 utilities, industries and agencies support the work at GT

• DOE Center in Photovoltaics and a Fuel Cell Research Center at GT

NEETRAC ProjectsSponsor Funded

IPIC SponsorsSponsors

Grant $$ Grant $$

Contract $$ Contract $$Technology

Program Accomplishments

Milestones:• IPIC consortium started in 2005, strong growth• 14 PhD degrees were awarded to IPIC students (2002-05)• IPIC faculty and students

– Published 150 papers in journals and conference proceedings (2004-05)– Filed for 14 patents/disclosures in 2004-05

• There are 36 PhD students and 3 MSc students in the IPIC program

Educational Program (includes Distance Learning)• 10 graduate courses in power• 6 undergraduate courses in power• 7 short courses in power

Research Program• Approximately 35 active projects within IPIC umbrella• Close working relationship with NEETRAC and PSERC• Includes three labs on campus, plus access to NEETRAC facilities• New laboratory facility for power electronics

Intelligent Power Infrastructure Consortium – Research Thrusts

Sensors, Communications,

Neural Nets, Monitoring

Power Systems

Engineering

PowerElectronics,Drives, Controls

Power line sensornetsWide area monitoringDistributed power line sensing

Power line communicationsNeural nets for system I/D and control

Wireless sensor networksSensorless motor fault detectionUnscheduled down-time identification

Neural network controls for PEComponent failure predictionPower and analog ICs

Active filtersMotor DrivesCurrent surge limitersHigh power inverters & dc/dc converters

D-FACTS devicesCurrent limiting conductorsFault current limitersPower quality and reliability

Wide area controlWide area protection

Power system operation and state estimation Protective relayingBulk power system reliability

Congestion managementSystem control and stability with FACTSDistributed energy sources

UTILITY APPLNS INDUSTRIAL APPLNS

Some Ongoing Power Electronics Projects at GT

• Current Limiting Conductors for Preventing Thermal Overload on Power Lines• Adaptive Critic Design Based Neurocontroller for Static Compensator• Micro-Engine Based Portable Power Pack• Optimal Allocation of Static and Dynamic VAR Resources • Determining Harmonic Contributions from Non-Linear Loads• Augmentation of Existing MV Transformers with Power Electronics• High Power DC/DC Converters• Quasi-Linear DC/DC Converters• Energy Harvesting System-In-Package for Wireless Micro-Sensors• An Accurate Integrated Li-Ion Battery Charger• Dynamically Adaptive Power Supply for Linear RF Power Amplifiers• Smart Capacitors – Condition Monitoring of Capacitors in PE Applications• Distributed Sensing Along Power Lines• Wireless Sensor Networks for Industrial and Utility Applications• Online Stator Winding Temperature Estimator for Induction Machines• Fault Detection in Brushless DC Motors• Offshore Wind Farm Architecture• Sustainable Single Home Power System for Off-Grid Villages

Distributed Control of Power Line Impedances

• Control how current flows on the power network, allowing automatic routing of current away from overloaded lines onto lines with available capacity (reliability benefit), and allowing dispatch of more economic generation resources along ‘non-optimal’ transmission corridors (economic benefit).

• Accomplished by controlling the impedance of power lines using multiple low-cost devices that clip on to existing power lines. The devices utilize simple commoditized technology and components, allowing rapid deployment with low capital and operating costs. Distributed solution allows mass manufacture and provides high reliability.

Couplers

xf

xo

IfIo

Current Limiting Conductors (CLiCs)

• It has not been possible to control current flows in a ‘meshed’ system, resulting in congestion, even as other lines remain under-utilized

• As current in a power line approaches thermal limit, line inductance needs to increase so that current is diverted automatically to lightly loaded lines

• Distributed Series Reactance modules clip on to the power line• Does not require communications or change in utility infrastructure

CLiCs – Summary of Results for IEEE 39 Bus System

Need for High Performance DC/DC Converters

• Demanding applications, such as medical imaging, fast processors, and pulsed loads are requiring new levels of performance from DC/DC converters

– Extremely low ripple voltages – Sub-cycle response and settling times (new

Intel processors consume 100 A with slew rates > 150A/µs and ΔV = 50 mV)

– High efficiency and small size• It is generally agreed that power supply technology

will be one of the limiting factors for the continued growth of VLSI technologies

• Conventional design approaches are not able to meet these needs easily

Quasi Linear DC/DC Converters

• A hybrid technique to realize linear power supply performance with switched mode DC/DC converter efficiency and size is proposed

DC/DC Converter

Input Voltage Linearizer Regulated

Voltage

Intermediate Pre-regulator

Voltage

Control

Quasi Linear Buck Converter

With Current Injection and Post-Regulation Only Post Regulation, No Current Injection

Buck regulator (12V → 5V) at 25 KHz switching frequency (2x47uF MLC Bulk Capacitors)Load switching at 100 Hz

Top trace (Pink): Buck output voltage, 50mV/div -> 2.5V/divMiddle trace (Green): Output load voltage, 50mV/div -> 2.5V/div

Lower trace (Blue): Load current 5A/div

0

50

100

150

200

250

300

350

0 1000 2000 3000 4000

t (hours)

ESR

(mΩ

)

Current/Voltage sensor

Pressure/Temperature sensor diaphragm

Smart Capacitors: Condition Monitoring of Electrolytic Capacitors

Sense:• ESR• Temperature• Pressure• Capacitance• Stress

Communicate:• Over existing power bus

Estimate:• ESR, C, Life

Induction Machine Condition Monitoring

• Thermal overload protection

• Insulation deterioration (35% of failures)– Turn-to-turn faults– Ground faults

• Broken rotor bars– Primarily in medium voltage copper bar rotors.

• Worn bearings (50% of failures)

• Unbalances and misalignment

Measure spectral components in current

Measure negative sequence in current

Measure positive sequence in current, resistance, temp.

Oscillating PM Generator (30W) Prototype Testing

Test generator

Interior rotor axial flux machine: low inertia

Stator 1 Stator 3

Stator 2

Rotor 1Rotor 2

400 W prototype by May

Prototype wireless sensor devices

• Transmitter Node

• Relay / Receiver Node

Wireless Sensor Network Architectural ConceptWireless Sensor Network Architectural ConceptBaseline Wireless Sensor Network Baseline Wireless Sensor Network

DB

Motor Control Center

Energy Management

Facility lighting and energy

Utility Substation

Switchboard

Separately mounted machine

control

Wireless communication also enables a wide range of cost effective conditions based maintenance features and

capabilities

Wireless SensorsWireless Communication Enabled

DB

Condition Based Diagnostics & Prognostics

Single Dwelling Energy Center for Off-Grid Villages

Other Sources

EnergyCenter

18VDC

100 W-hrStorage

WaterTank

PV Panel10/20 W

E-Charkha30-50 W

Room Lighting14 W x 3hr

Task/Mobile Lighting5 W x 4hr

Electronic Appliances10 W x 3hr

Water Purifier14 W x 1/2hr

Energy Budget ≅ 100 W-hrs/day

FlexibleSources

EnergyEfficientAppliances

Chip Integration of Power Management CircuitsChip Integration of Power Management Circuits

Ele

ctro

stat

ic

Pho

tovo

ltaic

Ther

moe

lect

ric

Energy-Harvesters

Boosting Charger

Power Conditioning

Thin-Film

Li-Ion

2.7 V – 4.2 V

Sys

tem

Loa

d

System-in-Package (SiP) Solution

+-

+-

Micro-Battery

+

-

Charger Regulator

Fuel

PowerGeneration

Source EnergyStorageDevice

+

-Load

Micro-Fuel CellMicro-Battery

Solar CellMEMS Generator

Micro-BatteryCapacitorInductor

SensorMeterADCGPS

Transceiver

Micro-BatteryCapacitorInductor

Power ManagementInterface

Self-Powered Chip

GoalsGoals

Portable (small & compact)Portable (small & compact)LightweightLightweightLongLong--Lasting (long life)Lasting (long life)SelfSelf--PoweredPoweredSelfSelf--SustainingSustaining

Prof. Gabriel A. Prof. Gabriel A. RincRincóónn--Mora Mora -- Georgia Tech Analog & Power IC Design Lab Georgia Tech Analog & Power IC Design Lab -- http://www.rinconhttp://www.rincon--mora.commora.com

2.5-5.5VPA

Adaptive Buck/BoostDC-DC Converter

Fixed Buck/BoostDC-DC Converter

Dynamic Buck/BoostDC-DC Converter

Power Management Core

LCD

Data

0110

01100.5-1VP/DSPCore

μ

0.9-

1.4V

Fuel

Cel

l

2.7-

4.2V

Thi

n-F.

Li-I

on

Chrgr

Extending Battery Life w/ Hybrid SourcesExtending Battery Life w/ Hybrid Sources

Managing HybridsManaging Hybrids Power ConditioningPower Conditioning Load ConditioningLoad ConditioningIntermittent, trickle Charger Intermittent, trickle Charger Adaptive DCAdaptive DC--DC ConvertersDC Converters ……

Harvesting EnergyHarvesting Energy

SystemSystem--onon--Chip (Chip (SoCSoC) & System) & System--inin--Package (Package (SiPSiP))

(p-type Silicon Substrate)p+p+p+ n+n+n+

n-w ellp+ p+

(Oxide)FOX FOX FOXFOX FOX

Metal 1Metal 2

n+n+FOX

n+FOX

Copper Inductor

(Passivation and Plastic Package)

Fuel In

++

p+

2 2

FOXgnd

p+p+p+ n+n+n+p+FOX FOX FOXFOX FOX FOX

gnd

Oxide & Passivation

Hot Surface

N-type SiP-type Si

Plastic Package

Cold Surface

200-

400

mμ

•• SiPSiP Technologies: Technologies: MEMS Devices, CMOS Circuits, & ThinMEMS Devices, CMOS Circuits, & Thin--Film Polymer LiFilm Polymer Li--Ion BatteriesIon Batteries

–– Energy SourcesEnergy Sources: : MEMS Thermoelectric & Electrostatic Harvesters &MEMS Thermoelectric & Electrostatic Harvesters &

DirectDirect--Methanol MicroMethanol Micro--Scale Fuel CellsScale Fuel Cells

–– Energy StorageEnergy Storage: : LiLi--Ion Batteries, Planar Cu Inductors, Ion Batteries, Planar Cu Inductors,

& Inductor/Capacitor Multipliers& Inductor/Capacitor Multipliers

–– Power Conditioning/DeliveryPower Conditioning/Delivery: : CMOS LinearCMOS Linear

& Switching Regulators & Trim& Switching Regulators & Trim--less Referencesless References

–– Load Conditioning/Energy TransferLoad Conditioning/Energy Transfer::

Low Voltage CMOS ChargersLow Voltage CMOS Chargers

Summary

• Georgia Tech has a strong and vibrant program in power technologies, including power electronics

• In addition to being strong in traditional technology areas, we have strength in emerging areas such as distributed control, neural networks, diagnostics, as well as newer fields such as utility applications

• Contact us ddivan@ece.gatech.edu if you have any questions.